Process for stabilizing antioxidant compounds, and aqueous compositions

ABSTRACT

The present invention is directed to a process for stabilizing antioxidant compounds comprising the step of adding to said compound, in an aqueous mean, at least an oxygen-removing compound, at least a metallic ion sequestering compound and at least an oxidation reaction reversing compound. The invention is particularly useful to stabilize antioxidant compounds such as levogyrous ascorbic acid (LAA), popularly known as “Vitamin C”, and the LAA associated with proantocianidines (OPC) for the preparation of pharmaceutical and cosmetic compositions.

FIELD OF THE INVENTION

The present invention relates to an improved process for stabilizingantioxidant compounds useful in cosmetic and pharmaceuticalcompositions.

BACKGROUND OF THE INVENTION

An antioxidant compound is any compound or mixture of compounds that,when in contact with the skin, is capable of protect the skin againstthe action of free radicals.

Antioxidant compounds such as levogyrous ascorbic acid (LAA), popularlyknown as “Vitamin C”, and proantocianidines (OPC) are widely used in thepharmaceutical and cosmetic industry since, among other characteristics,they act against the free radicals that speed up the aging process anddegeneration of the cells.

One of the greatest technical difficulties for the use of the aboveantioxidant compounds is their instability. The LAA, for example, caneasily be oxidized in the presence of atmospheric air, metallic ions orwater, thus being transformed into dehydroascorbic acid, in addition toother by-products resulting from the oxidation. Such transformationdiminishes its physiological properties, mainly under use conditionswhere the compound is exposed to the atmospheric air, metallic ions andwater such as, for example, when incorporated into a topic solution.

In a simplified way, the instability of an antioxidant is expressed as adecrease of its reducing ability before it is contacted with the skin.In the case of the LAA, its instability is expressed as a compounddegradation reaction.

In the case of the OPC's the instability occurs through anoligomerization reaction, followed by polymerization.

The LAA is often used in the form of its salts or esters due to thisinstability. The compositions prepared in this way attain stability forlong periods of time.

Many studies have been carried out in order to obtain an aqueouscomposition containing stable antioxidant compounds. Some alternativesto stabilize LAA are described in Brazilian Patent Applications PI9704418-0 and PI 9704728-7, filed by the same applicant of the presentapplication. In said patent applications, processes for stabilizinglevogyrous ascorbic acid (LAA) in a water-containing mean are disclosedcomprising the step of contacting the LAA with at least one compoundcapable of forming hydrogen bridges with the LAA.

Another procedure known from the art for stabilizing antioxidantsinvolves the association thereof with the compounds capable of revertingthe decomposition reaction, the so-called “reducing agents”. Once again,considering the LAA, for example, said compounds revert thedehydroascorbic acid formation reaction. However, the stabilizationthrough this process results in compositions unacceptable for cosmeticuse and many times unsuitable for medicinal use, since the requiredstoichiometric amount of reducing agents within the stoichiometry limitsof the reaction must be too high so that the desired results could beattained. Since the reducing agents are usually selected fromsulfur-containing compounds, the high content thereof in the resultantcompositions bring about an unpleasant odor and sometimes their use areeven legally forbidden. For example, in a solution containing aconcentration of 5% by weight of LAA, which is a concentration rangegenerally used in cosmetic-pharmaceutical products, contents ofapproximately 20% by weight of reducing agent should be required toensure the LAA stability.

Another prior art reference that can be cited and that teaches the useof reducing agents, is a work published by Wrinkler, B. S. (Biochim,Biophy, Acta, 1117, 1992, pages 287 through 290), in which a compound isdescribed (Glutathion) that can act as a reducer or reducing agent ofdehydroascorbic acid by transforming same into ascorbic acid in thestoichiometric form. Through this work it was discovered that it wasimpossible to keep stoichiometric amounts of the components to produce acosmetic composition since the Glutathion has an unpleasant odor whichis a characteristic of sulphidric compounds.

Therefore, it is an object of the present invention to provide a processfor stabilizing antioxidant compounds, that is, anti-free radicals or“anti-radicals”, that makes it possible to overcome the drawbacks commonto the known processes, among which the ones that use the so-calledreducing agents and, in a special way, that can result in stable,cosmetically more pleasant and more efficient compositions, alsosuitable for pharmaceutical use.

SUMMARY OF THE INVENTION

The present invention is directed to a process for stabilizingantioxidant compounds comprising the step of adding to said compound, inan aqueous medium, at least one oxygen-removing compound, at least onemetallic ion sequestering compound and at least one reducing agent.

The invention is also directed to compositions containing antioxidantcompounds stabilized according to the above process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a stability graph of compositions containing LAA accordingto formulas prepared in accordance with the invention during at least 90days at room temperature.

FIG. 2 shows the stability graph of compositions containing OPC that isan oligomer of grape seed, with which it is possible to measure thestability of said OPC.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have now found out that the association of atleast one antioxidant compound with an reducing agent, in a aqueousmedium, even without fulfilling the stoichiometry limits of theoxidation reaction, together with an oxygen-removing compound and ametallic ion sequestering agent makes it possible to stabilize saidantioxidant compound.

For the purposes of the present invention, some definitions of the termsused herein are given below.

A reducing agent is to be understood as any compound or mixture ofcompounds having a higher oxidation potential than the oxidationpotential of the oxidant to be stabilized so that the concentration ofantioxidant sub-compounds to be generated turns back to the originalantioxidant in its molecular form.

As to the oxygen-removing compound, or simply oxygen remover, is anycompound or mixture of compounds capable of decreasing the oxygensolubility in a medium containing water and the antioxidant to bestabilized.

The metallic ion sequestering, or simply sequestering agent, is anycompound or mixture of compounds having a high complexing constant andbeing effective for capturing and retaining such ions at pH values lowerthan 5.0. The effectiveness of the sequestering agent is defined by itsability to complexing the metallic ions present in a medium containingwater and the antioxidant to be stabilized, so that it can minimize andpreferably prevents the decomposition catalysis of any antioxidantpresent in said medium.

The invention is particularly suitable for providing the stabilizationof compositions containing antioxidant compounds such as levogyrousascorbic acid (LAA), or proantocianidines (OPC), or both, the resultantstability being effective for long periods of time.

In a first embodiment of the invention which is related to thestabilization of LAA in a aqueous medium, the oxygen-removing compoundis selected from the group consisting of glycols, more preferably amongpropylene glycol and butylene glycol as well as mixtures thereof, evenmore preferably the propylene glycol.

The metallic ion sequestering compound, on its turn, is selected fromthe group consisting of ethylene phosphonic acids, the salts andmixtures thereof, or from the group consisting of phosphonates includingdi-, tri-, tetra- and pentavalent acids, the salts and mixtures thereof.More specifically the compound capable of sequestering metallic ions canbe selected from the group consisting of sodium salt of1-hydroxyethylidene (1,1-diphosphonic) acid, ethylene diaminetetra(methylenephosphonic) acid, sodium salt of ethylene diamine tetra(methylenephosphonic) acid, diethylene diamine penta(methylenephosphonic) acid, sodium salt of diethylene diaminepenta(methylene phosphonic) acid, 1-hydroxyethylidene (1,1-diphosphonic)acid, and mixtures thereof. Preferably, 1-hydroxyethylidene(1,1-diphosphonic) acid is used as the metallic ion sequestering agent,which is commercialized under the name Dequest 2010 supplied byMONSANTO.

In accordance with a preferred embodiment of the invention, the processfor stabilizing antioxidant compounds comprises a first step wherein anaqueous solution containing the oxygen-removing compound and themetallic ion sequestering agent at a ratio ranging from 2500:1 to 50:1is prepared. In a second step, the antioxidant compound is then added tothe resultant solution in a aqueous medium.

In a third step, a LAA reducing agent is incorporated in the solutionprepared in the first step described above, at a ratio ranging from2520:1 to 20:1 related to the total mass of the oxygen-removing compoundplus the sequestering agent mass, and at a ratio ranging from 1:0.02 to3000:1, relating to the mass of the oxidizing compound. The greatadvantage achieved by the present invention is the notable stability ofthe LAA as time goes by. Compared to the compositions already known ofthe prior art containing this type of reducing agent, the inventionallows the use of reducing agent in significantly low amounts, thusmaking it possible to use same for cosmetic and/or pharmaceuticalcompositions, thus advantageously overcoming the aspect of unpleasantodor and the legal limitations concerning the concentration of reducingagent.

Suitable reducing agent are those conventionally known for that purposeand include sulfur-containing compounds, preferably those selected fromthe group consisting of sodium dithionite, bissodium bisulfites, calciumbisulfites, potassium bissulfites and still more preferably Glutathion,as well as mixtures thereof.

Usually, for obtaining a commercially suitable cosmetic compositioncontaining, for example, LAA as the antioxidant agent, the latter isused in a range from about 0.01% to about 30% and preferably from about0.5% to about 20%, by weight, while the oxygen-removing compound is usedin a range from about 10% to about 25%, preferably from about 16% toabout 19%, and the sequestering agent is used in a range from about0.01% to about 0.20%, preferably from about 0.10% to about 0.20%, allthe percentages being by weight, based on the total weight of thecomposition. The reducing agent is present at a concentration from about0.01% to about 0.5%, preferably from about 0.05% to about 0.2%. However,the amounts of these components will depend on the end uses for theresultant composition and should not limit the scope of the invention.

Among the antioxidant compounds of high importance in the cosmetic andpharmaceutical industry, the OPC's can also be cited, and they areadvantageously stabilized by the process of the present invention.Regarding those OPC's that can be stabilized by the process of theinvention, a more preferred embodiment of the process comprises a firststep of preparing a first composition comprising the oxygen-removingcompound, the sequestering agent and the reducing agent, which is thenadded to the OPC contained in an aqueous medium. In this preferredembodiment, the first composition contains other antioxidant, preferablythe LAA.

Although the reasons are not yet fully defined, it was noticed that thepresence of another antioxidant having characteristics similar to LAA inthe first composition favors the stabilization of the OPC's. Withoutbeing too theoretical, it is believed that there is a synergy betweenthe LAA present and the OPC's, resulting in an advantageously stablecomposition.

In a particularly advantageous way, an aqueous composition containingthe stabilized antioxidant in accordance with the present invention isused in a two-phase cosmetic composition. This kind of compositioncomprises, in a first phase, at least one antioxidant compound, anoxygen-removing compound, a metallic ion sequestering compound and areducing agent and, in a second phase, at least one hydrating compound.Preferably, the first and second phases are used at a weight ratiobetween them from 12:8 to 20:11, preferably of 16:9.

The two-phase composition described above has proved to be particularlysuitable for regions where the skin is more delicate and, consequently,where it requires special care. “More delicate skin” must be understoodas the one more sensitive to the use of formulations that containantioxidant compounds, emulsifying systems, fragrances, preservatives,cosmetic agents, among others. In the case of some antioxidantcompounds, the use of high concentrations and the nature of thesecompounds can cause a higher exfoliation and irritation to the user skinand a discomfort sensation.

For example, the delicate region around the eyes as well as other areasof the body require special care since the skin is thinner and fragile.The skin structure in this region is different: the epidermis and dermisare thinner, thus being more susceptible to the external aggressions andfacilitating to the appearance of wrinkles and expression marks.Collagen and elastin, that contribute to a higher skin stiffness andelasticity are also present in a lower amounts that helps tocharacterize the delicacy of the region.

Hydrating agents as herein defined and useful for the present inventionare those compounds or mixtures of compounds capable of increasing thewater retention and restructuring the skin barrier for preventing theloss of water.

In a preferred way to formulate said two-phase composition, its firstphase comprises an aqueous composition comprising an amount of 0.2 10%,preferably from 0.5 and 2%, of acid ascorbic and about 0.001 to 2.2%,preferably from 0.01 to 1.0%, of OPC's, particularly OPC from grapeseed, and in its second phase a mixture of hydrating agents such asglycerin present at a concentration of 1.0 to 10% and 0.5 to 3.0% ofceramides contained in a liquid crystal emulsion, also called lamellarceramide.

The lamellar ceramides help to restore the skin protection barrier, thusreinforcing the skin structure and consequently preventing the excessiveloss of water. Together with glycerin, which is a soft hydrating agentand that increases the retention of water by the skin, it improves thehydration and softness thereof. The high glycerin concentration alsoprovides a high hydration potential.

In as still more preferred way, the two-phase composition containingantioxidants stabilized in accordance with the invention is in the formof a homogeneous emulsion comprising an emulsifying system including atleast two emulsifiers, one of which is selected from the groupconsisting of organosilicones of the copolyol family, preferably cetyldimethicone copolyol, and a second one the molecular structure of whichis similar to the natural skin lipids, preferably selected from alipophylic stearic acid derived from a polyglycerol, more preferablypolyglycerol-4-isostearate. The emulsifying system is advantageouslyadded at a concentration of 0.5 to 8% by weight, based on the totalweight of the composition.

In this emulsion form, the antioxidants together with the emulsifyingsystem form micro-particles the size of which provides the emulsion witha better effectiveness and homogeneity. Since they are protected inmicro-particles, the antioxidants, especially when it is OPC of grapeseed, act on the walls of the blood vessels reinforcing same, whatcontributes to reduce the appearance of dark rings under the eyes andavoid the formation of such dark rings. Preferably, the emulsionparticles are smaller than 3 μm, more preferably smaller than 2 μm, andstill more preferably smaller than 1 μm.

The cosmetic composition as herein described may also comprise in itssecond phase from 13 to 25%, preferably from about 16 to 22% ofemollients, from about 1 to 4% of an anti-radical agent, more preferablyfrom 1.5 to 3.5% of Vitamin E, from about 0.001 to 0.3% of apreservative, more preferably 0.01 to 0.3% of sodium benzoate, and fromabout 0.05 to 0.6% of a thickening agent, more preferably from about0.15 to 0.4% of colloidal silicon dioxide.

It was observed that the selection of the preservative agent is animportant factor for the stabilization of the emulsion micro-particlesdue to its stripping ratio between the water and oil phases.

The illustrative examples and tests given below will better describe thepresent invention. However, the illustrated data and procedures merelyrefer to some embodiments of the present invention and should not beunderstood as limiting the scope of the invention.

EXAMPLE 1

Comparative tests carried out by the inventors confirm the importantpaper of the reducing agent in the stabilization of antioxidants as perinformation obtained by Wrinkler B. S. in his work cited herein. A firsttest was carried out in order to determine the degradation kinetics of a10% LAA solution in water-containing medium (m/v) under ultravioletradiation, using a ultraviolet spectrophotometer, for 60 minutes. Animmediate degradation of the LAA was observed, wherein a concentrationof molecular LAA of about 9.58% (m/v) remained.

A stoichiometric amount of the reducing agent of the oxidation reaction,that is, Glutathion, was added to the previous post-irradiated solution.The resultant solution was irradiated with ultraviolet radiation forfurther 60 minutes. By analyzing the remaining LAA, it could be noticedthat 9.50% (m/v) thereof was still present. Therefore, the degradationof the LAA is dramatically minimized after the reducing agent is added.

In a third test, a 10% LAA solution was prepared in a water-containingmedium (m/v) with a stoichiometric amount of the reducing agentGlutathion. The solution was irradiated with ultraviolet radiation for60 minutes: By analyzing the remaining LAA, a high content of 9.98%(m/v) was attained, thus confirming that the reducing agent inhibits thedegradation of LAA. However, the use of said compound in stoichiometricamounts still presents the already mentioned disadvantages.

For the purpose of evaluating the invention, stability tests of theantioxidants LAA and LAA associated with OPC's in a water-containingmedium have been carried out. Twelve different formulas were prepared inaccordance with the invention, the chemical compositions of which aswell as the obtained results are discussed in the following Tables I andII.

TABLE I Glutathion (% OPC m/v) reducing (% m/v) LAA (% m/v) RemainingFormula agent Antioxidant Antioxidant LAA (% m/v) 1 0.05 0 10 9.82 20.10 0 10 9.92 3 0.05 2 10 9.82 4 0.10 2 10 10.00

Table I shows the stability results of the LAA and OPC's measured by therespective remaining percentages, wherein formulas 1 through 4 have beenprepared in accordance with the invention; formulas 1 and 2 includingonly LAA and formulas 3 and 4 comprising LAA associated with OPC's.

In the above tests, formulas 1 through 4 also comprise propylene glycolas an oxygen-removing compound, 2010 Dequest as the metallic ionsequestering agent and water.

It can be noticed from Table I that formulas 1 through 4 prepared inaccordance with the invention show a LAA stability very close to 100%compared with the initial concentration.

Next, tests with further eight formulas have been carried out toevaluate the stability of LAA plus a gelling agent (Modified XanthaneGum). Formulas 5, 8, 11 and 12 include sodium dithionite as an reducingagent, and formulas 6, 7, 9 and 10 use, again, Glutathion as thereducing agent, as shown in Table II

TABLE II Sodium Glutathion (% dithionite (% LAA Remaining m/v) reducingm/v) reducing (% m/v) LAA Formulas agent agent Antioxidant (% m/v) 50.00 0.05 5.0 5.0 6 0.10 0.00 5.0 5.0 7 0.05 0.00 5.0 5.0 8 0.00 0.105.0 5.0 0 0.05 0.00 10.0 10.0 10 0.10 0.00 10.0 10.0 11 0.00 0.05 10.010.0 12 0.00 0.10 10.0 10.0

Table II shows the formulas evaluated as to stability of the LAA underultraviolet radiation for 60 minutes. All the formulas contain propyleneglycol, modified xanthane gum, Dequest 2010, PVA and water.

The purpose of the tests carried out with the compositions shown inTable II was to confirm that the stabilization of the LAA issuccessfully obtained with different reducing agents.

Sodium dithionite was used in formulas 5, 8, 11 and 12, resulting in apercentage of remaining LAA of about 100% after 90 days, which meansthat LAA practically does not undergo any degradation during at least 90days at room temperature, maintaining the initial concentrations of itsmolecular form.

The reducing agent employed in formulas 6, 7, 9 and 10 is Glutathion.From FIG. 1, it can be noticed that the percentage of remaining LAA informulas 6 and 7 remains around 100% even in the presence of anotherreducing agent,

FIG. 2 shows the stability graph of compositions containing OPC, whichis a grape seed oligomer, through which it is possible to measure thestability of said OPC.

It can be noticed that the OPC's stability under the sun light is of atleast 70% and around 80% in the dark, that latter being the normalcondition for the final commercial product, thus demonstrating that theresult is favorable for the invention.

EXAMPLE 2

A water-in-oil emulsion was prepared which comprises in a first phase:

Ingredient % Mass Function Water About 70 vehicle Butylene glycol 1 to 4Oxygen-removing compound Glutathion 0.1 reducing agent1-Hydroxyethylidene (1,1- 0.15 Metallic ion diphosphonic) acid(Dequest ®) sequestering agent LAA from 1 to 30 Antioxidant agent Grapeseed OPC 0.3 Antioxidant agentand, in a second phase

Ingredient % Mass Function Glycerin 7.0 Hydrating agent LamellarCeramides 1.0 Hydrating agent Cetyl dimethicone copolyol 2.0 EmulsifierTriglycerol isostearate 4 2.0 Emulsifier Vitamin E 2.0 AntioxidantSodium benzoate 0.3 Preservative Colloidal silicon dioxide 0.3Thickening agent Magnesium sulphate 0.7 Thickening agent CyclomethiconeD5/d6 13.5 Emollient Isohexadecane 5.0 Solvent

A panel was composed in a blind study, with 80 female volunteers withages ranging between 25 and 65 years, evaluated at two different times:after the fifteenth day of use (T15) and at the 30th day of use (T30).The product was supplied at ratios of about 16:9 of the first phase tothe second phase and according to the composition described in theexample above. The results of this evaluation are given in table IIIwhere the expressed percentages refer to the percentage of users thatperceived the occurrence of the corresponding benefit.

TABLE III Evaluation of the product performance by the physician T15 T30Wrinkles 16.6% 31.2% Flaccidity 8.7% 16.6% Drying 11.2% 63.7% Ringsunder the eyes 17.5% 27.5% Edema 12.5% 22.5%

Amongst the product beneficial effects, including those evaluated thetest, the following should be stressed out:

it alleviated the skin aging marks around the eyes, such as wrinkles andflaccidity;

it reduced the dark rings and pockets under the eyes;

it improved the stiffness of the skin;

1. A process for stabilizing antioxidant compounds selected from thegroup consisting of levogyrous acid (LAA), proanthocyanidines (OPCs) andmixtures thereof, comprising: contacting said antioxidant compounds, inan aqueous medium, with an oxygen-removing compound, a metallic ionsequestering compound and a reducing agent; wherein the oxygen-removingcompound is a glycol; further wherein the metallic ion sequesteringcompound is selected from the group consisting of sodium salt of1-hydroxy ethylidene (1,1-diphosphate) acid, ethylene diaminetetra(methylenephosphonic) acid, sodium salt of ethylene diaminetetra(methylenephosphonic) acid, diethylene diaminepenta(methylenephosphonic) acid, sodium salt of diethylene diaminepenta(methylene phosphonic) acid, hydroxyethylidene (1,1-diphosphate)acid and mixtures thereof.
 2. A process in accordance with claim 1,wherein the antioxidant is LAA.
 3. A process in accordance with claim 1,wherein the antioxidant compounds are a mixture of LAA andproanthocyanidines (OPCs).
 4. A process in accordance with claim 1,wherein the oxygen-removing compound is selected from the groupconsisting of propylene glycol, butylene glycol and mixtures thereof. 5.A process in accordance with claim 1, wherein the metallic ionsequestering agent is 1-hydroxyethylidene (1,1-diphosphonic) acid.
 6. Aprocess in accordance with claim 1, wherein the reducing agent isselected from the group consisting of sodium dithionite, sodiumbisulfites, calcium bissulfites, potassium bissulfites, glutathione, andmixtures thereof.
 7. A process in accordance with claim 6, wherein thereducing agent is glutathione or sodium dithionite.
 8. A process inaccordance with claim 1, comprising a first step of preparing an aqueoussolution containing the oxygen-removing compound, the metallic ionsequestering agent and the reducing agent, and a second step of addingthe antioxidant to the thus prepared composition, in an aqueous medium.9. A process in accordance with claim 8, wherein the composition formedin the first step comprises the oxygen-removing compound in a range fromabout 10% to about 25%, the metallic ion sequestering agent in a rangefrom about 0.01% to about 0.20%, the reducing agent at a concentrationof about 0.01% to about 0.5%, the content of the antioxidant being fromabout 0.01% to about 30%, all the percentages being by weight based onthe total weight of the composition.
 10. A process in accordance withclaim 9, wherein the composition formed in the first step comprises theoxygen-removing compound in a range from about 16% to about 19%, themetallic ion sequestering agent in a range from about 0.10% to about0.20% and the reducing agent at a concentration from about 0.05% toabout 0.2%, the content of the antioxidant being from about 0.5% toabout 20% by weight.
 11. A process in accordance with claim 8, whereinthe antioxidant is an OPC, and wherein said first composition alsocomprises LAA.
 12. An aqueous composition comprising at least oneantioxidant compound selected from the group consisting of levogyrousascorbic acid (LAA), proanthocyanidines (OPCs) and mixtures thereof, anoxygen-removing compound, a metallic ion sequestering agent and anoxidation reaction reverting compound; wherein the oxygen-removingcompound is a glycol; further wherein the metallic ion sequesteringcompound is selected from the group consisting of sodium salt of1-hydroxy ethylidene (1,1-diphosphate) acid, ethylene diaminetetra(methylenephosphonic) acid, sodium salt of ethylene diaminetetra(methylenephosphonic) acid, diethylene diaminepenta(methylenephosphonic) acid, sodium salt of diethylene diaminepenta(methylene phosphonic) acid, hydroxyethylidene (1,1-diphosphate)acid and mixtures thereof.
 13. An aqueous composition in accordance withclaim 12, wherein the antioxidant is LAA.
 14. An aqueous composition inaccordance with claim 12, wherein the antioxidant compounds are amixture of LAA and proanthocyanidines (OPCs).
 15. An aqueous compositionin accordance with claim 12, wherein the oxygen-removing compound isselected from the group consisting of propylene glycol, butylene glycoland mixtures thereof.
 16. An aqueous composition in accordance withclaim 12, wherein the metallic ion sequestering agent is1-hydroxyethylidene (1,1-diphosphate) acid.
 17. An aqueous compositionin accordance with claim 12, wherein the oxidation reaction revertingcompound is selected from the group consisting of sodium dithionite,sodium bissulfites, calcium bissulfites, potassium bissulfites,glutathione, and mixtures thereof.
 18. An aqueous composition inaccordance with claim 17, wherein the oxidation reaction revertingcompound is glutathione or sodium dithionite.
 19. An aqueous compositionin accordance with claim 13, comprising from about 0.01% to about 30% ofLAA, from about 10% to about 25% of an oxygen-removing compound, fromabout 0.01% to about 0.20% of a metallic ion sequestering agent, andfrom about 0.01% to about 0.5% of an oxidation reaction revertingcompound.
 20. A two-phase aqueous cosmetic composition, comprising, in afirst phase, at least one antioxidant compound selected from the groupconsisting of levogyrous ascorbic acid (LAA), proanthocyanidines (OPCs)and mixtures thereof, an oxygen-removing compound, a metallic ionsequestering agent and a reducing agent and, in a second phase, at leastone hydrating compound; wherein the oxygen-removing compound is aglycol; further wherein the metallic ion sequestering compound isselected from the group consisting of sodium salt of 1-hydroxyethylidene (1,1-diphosphate) acid, ethylene diaminetetra(methylenephosphonic) acid, sodium salt of ethylene diaminetetra(methylenephosphonic) acid, diethylene diaminepenta(methylenephosphonic) acid, sodium salt of diethylene diaminepenta(methylene phosphonic) acid, hydroxyethylidene (1,1-diphosphate)acid and mixtures thereof.
 21. A two-phase composition in accordancewith claim 20, wherein the weight ratio between the first and secondphases is from about 12:8 to 20:11.
 22. A two-phase composition inaccordance with claim 20, wherein the oxygen-removing compound isselected from the group consisting of propylene glycol, butylene glycoland mixtures thereof.
 23. A two-phase composition in accordance withclaim 20, wherein the metallic ion sequestering agent is 1-hydroxyethylidene (1,1-diphosphate) acid.
 24. A two-phase composition inaccordance with claim 20 wherein the reducing agent is selected from thegroup comprising sodium dithionite, sodium bissulfites, calciumbissulfites, potassium bissulfites, glutathione, and mixtures thereof.25. An aqueous two-phase composition in accordance with claim 24, thereducing agent is glutathione or sodium dithionite.
 26. A two-phasecomposition in accordance with claim 20, wherein the hydrating compoundis glycerin.
 27. A two-phase composition in accordance with claim 20,wherein the second phase comprises ceramides in a liquid crystalemulsion form.
 28. A two-phase composition in accordance with claim 27,wherein, in the first phase, an aqueous composition comprising an amountof 0.2 to 10% of ascorbic acid and about 0.001 to 2.2% of OPC's and, inthe second phase, glycerin in a range from 1.0 to 10%, and 0.5 to 3.0%of ceramides contained in a liquid crystal emulsion, all percentagesbeing based on the total weight of the composition.
 29. A two-phasecomposition in accordance with claim 20, wherein, in its second phase,about 13 to 25% of emollients, about 1 to 4% of an anti-radical agent,about 0.001 to 0.3% of a preservative, and about 0.05 to 0.6% of athickening agent.
 30. A composition in accordance with claim 20, whereinsaid composition is in the form of an homogeneous emulsion containing anemulsifying system comprising a first emulsifier includingorganosilicones and a second emulsifier.
 31. A composition in accordancewith claim 30, wherein said organosilicone is cetyl dimethicone copolyoland the second emulsifier ispolyglycerol-4-isostearate.
 32. Acomposition in accordance with claim 30, wherein said composition is inthe form of micro-particles smaller than 3 μm.
 33. A composition inaccordance with claim 32, wherein the micro-particles have a sizesmaller than 1 μm.
 34. A process in accordance with claim 1, wherein theoxygen-removing compound is propylene glycol.
 35. An aqueous compositionin accordance with claim 12, wherein the oxygen-removing compound ispropylene glycol.
 36. A two-phase composition in accordance with claim20, wherein the oxygen-removing compound is propylene glycol.